Presentation on theme: "Sawing and Cutting Tools"— Presentation transcript:
1 Sawing and Cutting Tools Unit 11Sawing and Cutting ToolsHandsaws • Sawing Technique • Use and Care of Handsaws • Other Cutting Tools
2 Although the basic construction of handsaws is similar, many differences are found in the length and shape of the blade and the number and shape of the teeth.The main parts of a handsaw are the blade (including the toe and heel of the blade), teeth, back, and handle. See Figure Although the basic construction of all hand-saws is similar, there are many differences in the length and shape of the blade and the number and shape of the teeth. Most handsaws have a straight back, but skew-back saws (curved-back) are also available.
3 High-quality saws have a taper-ground blade High-quality saws have a taper-ground blade. The blade is thinner along its back than at its cutting edge.The kerf (cut made by a handsaw) is wider than the thickness of a saw blade to allow the blade to move freely through the material being cut. If this were not the case, the wood fibers pressing against the blade would cause the saw to bind, making the cutting action difficult. Teeth of a saw are set (alternately bent from side to side), which provides a wider kerf than the blade thickness. High-quality saw blades are taper ground. See Figure The blade back is thinner than the blade at the cutting edge, requiring less set in the teeth.
4 An 8-point saw has larger teeth and fewer teeth per inch than an 11-point saw. A saw usually has a number printed on its blade in-dicating the number of teeth or points per inch. See Figure The lower the number, the larger the teeth, and the rougher the cut that is made. For example, an 8-point saw has larger teeth than an 11-point saw and produces a rougher cut than an 11-point saw.
5 The knife-shaped teeth of a crosscut saw are effective for cutting across the grain. Most saws used in carpentry are crosscut saws. The teeth of crosscut saws are shaped like knives to cut across the wood fibers and grain of the wood. See Figure Crosscut saws should be held at a 45° angle to the work surface to cut efficiently.
6 Compass saws are used to cut curves or internal openings. A compass saw is used to saw curves, holes, and other internal openings. See Figure A compass saw has a 12″ or 14″ blade with 8 or 10 points per inch. When cutting an internal opening, a hole is first drilled in the material to start the compass saw. A compass saw can also be used to start saw cuts in tight spaces where a regular saw will not fit.
7 Backsaws may be used with a miter box to cut accurate angled or straight cuts in finish work. A backsaw is used with a miter box to make fine cuts in finish work. See Figure The blade of a backsaw is 10″ to 26″ long and 3 1/4″ to 6″ wide, and has 10 to 14 points per inch. The back of a backsaw is reinforced to stiffen the blade for accurate straight cuts. A large version of a backsaw is a miter saw.
8 Dovetail saws are used to make fine cuts in molding or other small trim materials. A dovetail saw has a reinforced back, round handle, and narrow blade. See Figure Dovetail saws are used to make fine cuts in molding and other small trim mate-rials. The type of dovetail saw used most often has a 2″ × 10″ blade, with 15 points per inch.
9 Coping saws are used to make fine, irregular cuts in thin materials. A coping saw is used to cut curves and irregular lines in thin material. See Figure Coping saws are fre-quently used to cut coped joints when fitting the inside corners of molding. The coping saw preferred by most carpenters has a 1/8″ × 6 3/8″ blade. The blade can be adjusted to make angled cuts easier.
10 The chisel‑shaped teeth of ripsaws are effective for cutting with the grain. Ripsaws are designed to cut with the wood grain. Ripsaw teeth are shaped like chisels, to be effective for cutting with the wood fibers. See Figure Most ripsaws have a 26″ blade with 5 1/2 points per inch. A ripsaw should be held at a 60° angle to the work surface for efficient cutting action. Sawing with the grain takes more time and effort than sawing across the grain.
11 The proper sawing technique results in accurate cuts while minimizing accidents. The proper sawing technique ensures quick, clean, and accurate cuts in wood or other material with minimal effort. See Figure In addition, the proper sawing technique prevents hand lacerations from the saw teeth. Use the following technique when cutting with a crosscut saw or ripsaw:1. Place the saw teeth along the waste side of the line. Press your thumb or side of hand lightly against the blade when starting the cut.2. Pull back on the saw, holding up on the handle so the blade moves lightly back and forth until an initial saw kerf has been made.3. Move the nonsawing hand a safe distance away from the blade and continue cutting. Adjust the cutting angle for crosscut saws and ripsaws to 45° and 60°, respectively.
12 Hacksaws are used to cut metals. Two metal-cutting saws are the hacksaw and nail saw. A hacksaw is used to cut metal materials such as framing members and door thresholds. See Figure
13 Nail saws are used to cut nails so that framing members can be more easily separated. A nail saw is used to cut nails holding together framing members. See Figure The nail saw blade fits into a metal or plastic handle similar to that of a com-pass saw.
14 Wood chisels include flooring chisels and butt chisels Wood chisels include flooring chisels and butt chisels. A flooring chisel is used for rough work. A butt chisel is used to mortise lumber for door hinges and other types of finish hardware.Wood chisels are hand tools used for rapid removal of waste stock. See Figure Some chisels, such as flooring chisels, are designed for rough work. Other chisels are designed for finish work. A butt chisel is a wood chisel used for mortising door hinges, flush bolts, and other kinds of finish hardware. Butt chisels have a plastic or wood handle that holds the blade. The end of a chisel handle is typically protected by a steel cap, which receives the direct hammer blow.
15 When using a wood chisel, keep both hands behind the cutting action of the chisel, and cut away from the body.Wood chisels must be kept sharp. A dull chisel requires greater effort to use, results in poor work, and provides greater potential for injury. Consider the following safety precautions when using wood chisels:• Carry wood chisels by the handle with the blade pointing downward. Do not carry chisels in pockets.• Remove wood chisels from service if handles are loose or cracked.• A wood chisel should only be used for its designed purpose. Do not use a chisel as a wedge or pry bar.• When using a wood chisel, always keep both hands behind the cutting edge of the chisel. Always cut away from your body. See Figure
16 Cold chisels are used to cut metals and chip concrete Cold chisels are used to cut metals and chip concrete. Cold chisel heads must be properly ground to prevent chips from becoming detached from a mushroomed head.Cold chisels are forged from special hardened and tempered alloy steel, and are used to cut through nails and other metals, stucco, and plaster, and to chip con-crete. Cold chisels are available in 1/4″ to 1″ widths and 6″ to 12″ lengths. See Figure
17 Utility knives are used to cut materials such as gypsum board, fiberboard, and insulation. Carpenters use knives for cutting gypsum board, insulation, and many other construction materials. A retractable-blade utility knife is frequently used. See Figure The blade is retracted into the knife body when it is not being used. Additional blades are stored in the handle.
18 Aviation snips are used to cut metal framing members. Aviation snips are used to make straight or angled cuts in light-gauge sheet metal, and are available in a 10 1/2″ length. The compound action of aviation snips results in maximum cutting power with minimal effort. See Figure 11-7.
19 Side-cutting pliers are commonly used for twisting or cutting wires and pulling or cutting nails. Side-cutting pliers are used for cutting and twisting wire. See Figure In addition, side-cutting pliers are useful for cutting off or pulling out nails.